X and Y chromosome loss as sole abnormality in acute non-lymphocytic leukemia (ANLL)

Mosaic loss of chromosome Y promotes leukemogenesis and clonal hematopoiesis

Mosaic loss of chromosome Y (mLOY) in blood cells is one of the most frequent chromosome alterations in adult males. It is strongly associated with clonal hematopoiesis, hematopoietic malignancies, and other hematopoietic and nonhematopoietic diseases. However, whether there is a causal relationship between mLOY and human diseases is unknown. Here, we generated mLOY in murine hematopoietic stem and progenitor cells (HSPCs) with CRISPR/Cas9 genome editing. We found that mLOY led to dramatically increased DNA damage in HSPCs. Interestingly, HSPCs with mLOY displayed significantly enhanced reconstitution capacity and gave rise to clonal hematopoiesis in vivo. mLOY, which is associated with AML1-ETO translocation and p53 defects in patients with acute myeloid leukemia (AML), promoted AML in mice. Mechanistically, loss of KDM5D, a chromosome Y-specific histone 3 lysine 4 demethylase in both humans and mice, partially recapitulated mLOY in DNA damage and leukemogenesis. Thus, our study validates mLOY as a functional driver for clonal hematopoiesis and leukemogenesis.

Clinical and biological significance of isolated Y chromosome loss in myelodysplastic syndromes and chronic myelomonocytic leukemia. A report from the Spanish MDS Group

Isolate loss of chromosome Y (-Y) in myelodysplastic syndromes (MDS) is associated to a better outcome but it is also well described as an age-related phenomenon. In this study we aimed to analyze the prognostic impact of -Y in the context of the IPSS-R cytogenetic classification, evaluate the clinical significance of the percentage of metaphases with isolated -Y, and test whether finding -Y may predispose to over-diagnose MDS in patients with borderline morphological features. We evaluated 3581 male patients from the Spanish MDS Registry with a diagnosis of MDS or chronic myelomonocytic leukemia (CMML). -Y was identified in 177 patients (4.9%). Compared with the 2246 male patients with normal karyotype, -Y group showed a reduced risk of leukemic transformation that did not translate into a survival advantage. The overall survival and the risk of leukemic transformation were not influenced by the percentage of metaphases with -Y. The -Y group was not enriched in patients with minor morphologic traits of dysplasia, suggesting that the better outcome in the -Y group cannot be explained by enrichment in cases misdiagnosed as MDS. In conclusion, our results support the current recommendation of classifying patients with -Y within the very good risk category of the IPSS-R for MDS and rule out a selection bias as a possible explanation of this better outcome. An analysis of the molecular basis of MDS with isolated -Y would be of interest as it may provide a biological basis of protection against progression to acute leukemia.

Sex chromosome loss after allogeneic hematopoietic stem cell transplant in patients with hematologic neoplasms: a diagnostic dilemma for clinical cytogeneticists

BACKGROUND

Sex chromosome loss (SCL), including loss of an X chromosome (-X) in females and loss of the Y chromosome (-Y) in males, resulting in a karyotype of 45,X, rarely occurs in patients post an allogeneic hematopoietic stem cell transplant (alloHSCT). However, origin of this abnormal clone and its clinical significance remains unknown.

RESULTS

We present 12 cases with SCL who underwent alloHSCT; 9 patients (4 men and 5 women with a median age of 56 years) developed isolated SCL after alloHSCT (Group I), and 3 patients (all women with a median age of 58 years) had a SCL before undergoing alloHSCT after which SCL disappeared (Group II). The primary neoplasms included chronic lymphocytic leukemia (n = 5), acute myeloid leukemia (n = 5), chronic myelogenous leukemia with nodal marginal zone lymphoma (n = 1) and Hodgkin lymphoma (n = 1). According to the donor/recipient relationship, their alloHSCT can be divided into sex-matched, HLA-matched, unrelated donors (n = 2); sex-mismatched, HLA-matched, unrelated donors (n = 4); sex-mismatched, HLA-matched, related donors (2 HLA-identical and 2 HLA-haploidentical cases) and sex-matched, HLA-matched, related donors (2 HLA-haploidentical cases). In Group I, isolated SCL was first detected with a median interval of 3 months (range 1 to 42 months) after the alloHSCT. By the end of clinical follow-up in patients in Group I, 7 patients expired with a median overall survival of 45 months (range 3 to 108 months) after alloHSCT and 33 months (range 0 to 66 months) after SCL detection. In Group II, 1 patient expired with a survival time of 54 months after the alloHSCT. Detection of SCL after alloHSCT can be transient, intermittent or persistent.

CONCLUSIONS

Interpretation of SCL is challenging in the context of alloHSCT. Chimerism testing is useful in determining the origin of SCL. In the case of SCL with donor/recipient chimerism, deduction of the SCL origin by all means and use of "-?X" or "-?Y" in the ISCN nomenclature are recommended. Clinical follow-up with closely monitoring the SCL by both cytogenetic and molecular analyses is needed.

Loss of Y Chromosome in Peripheral Blood of Colorectal and Prostate Cancer Patients

Background

Although age-related loss of chromosome Y (LOY) in normal hematopoietic cells is a well-known phenomenon, the phenotypic consequences of LOY have been elusive. However, LOY has been found in association with smoking, shorter survival and higher risk of cancer. It was suggested that LOY in blood cells could become a predictive biomarker of male carcinogenesis.

Aims, Methods & Findings

To investigate the association of LOY in blood cells with the risk for development of colorectal (CC) and prostate cancers (PC), we have analyzed DNA samples from peripheral blood of 101 CC male patients (mean age 60.5±11.9 yrs), 70 PC patients (mean age 68.8±8.0 yrs) and 93 healthy control males (mean age 65.8±16.6 yrs). The methodology included co-amplification of homologous sequences on chromosome Y and other chromosomes using multiplex quantitative fluorescent (QF) PCR followed by automatic detection and analysis on ABI 3500 Genetic Analyzer. The mean Y/X ratio was significantly lower in the whole group of cancer patients (0.907±0.12; p = 1.17x10^-9) in comparison to the controls (1.015±0.15), as well as in CC (0.884±0.15; p = 3.76x10^-9) and PC patients (0.941±0.06; p = 0.00012), when analyzed separately. Multivariate logistic regression analysis adjusting for LOY and age showed that LOY is a more significant predictor of cancer presence than age, and that age probably does not contribute to the increased number of subjects with detectable LOY in cancer patients cohort.

Conclusion

In conclusion, our results support the recent findings of association of LOY in blood cells with carcinogenesis in males.

Microchimeric Cells, Sex Chromosome Aneuploidies and Cancer

The phenomenon of feta-maternal microchimerisms inspires numerous questions. Many questions remain to be answered regarding this new avenue of genetics. The X and Y chromosomes have been associated with malignancy in different types of human tumors. We aimed to investigate the numerical aberrations of chromosomes X and Y in lung cancer (LC) and bladder cancer (BC) and review recent evidence for possible roles of microchimeric cells (McCs) in these cancers. We carried out cytogenetic analysis of the tumor and blood sampling in 52 cases of people with BC and LC, and also with 30 healthy people. A total of 48 (92.3 %) of the patients revealed sex chromosome aneuploidies (SCAs). A total SCAs was found in 9.8 % of 2282 cells that were analyzed as one or more cells in each case. The 68 and 95 SCAs were found in the 1952 (8.4 %) cells in peripheral blood, and 41 and 19 SCAs in the 330 (18.2 %) cells in the tumoral tissues respectively. There was a significant difference in the frequencies of SCAs between the patients and the control groups determined by the Fischer's Exact Test (p < 0.0001). The frequencies of SCAs were higher in the tumoral tissues than in the blood (p < 0.0001). There was a significant difference in the frequencies of SCAs between the tumor and blood tissues, and this was higher in the tumor tissue (p < 0.0001). In general, 78.9 % (41) of the 52 patients with LC and BC had X and Y chromosome monosomies. Largely a Y chromosome loss was present in 77.8 % of the men, and the 47, XXY karyotype was found in 33.3 % of them. The second most common SCA was monosomy X, and was found in 71.4 % of the women. McCs were observed in 26.9 % of the 52 patients, and the frequencies of McCs were higher in the blood than in the tissues (p < 0.0001). XY cells were identified in the lung and bladder tissues of the women who had been pregnant with boys, but not in those who had not. There was a significant difference in the frequencies of McCs between the LC and BC patients (p < 0.0005). We speculate that the microchimerism could have a general beneficial role in cancer, in which some sites may not be evident because of an allogeneic maternal immune reaction that hastens cancer development. A further understanding of McCs may help in anticipating its implications in cancer. Our results may suggest that SCAs may be contributing factors in the development of LC and BC, and aneuploidies of X and Y chromosomes play a role in the pathogenesis of cancers.

The significance of isolated Y chromosome loss in bone marrow metaphase cells from males over age 50 years

To further investigate the potential clinical significance of Y chromosome loss as the sole bone marrow karyotype change, we studied 161 Mayo Clinic male patients with 75% or more metaphase cells with Y loss, and correlated the percent Y loss with age and hematopathologic review. In patients with a lymphoproliferative or plasma cell disorder, the negligible proportion of bone marrow involvement cannot account for the observed high proportion of -Y cells. In males with myeloid disease, Y loss appears to often represent the abnormal myeloid clone, which may also harbor acquired genetic changes that are not observed by conventional cytogenetic analysis.

Donor cell leukemia: a review

Relapse of acute leukemia following hematopoietic stem cell transplantation (HSCT) usually represents return of an original disease clone, having evaded eradication by pretransplant chemo-/radiotherapy, conditioning, or posttransplant graft-versus-leukemia (GVL) effect. Rarely, acute leukemia can develop de novo in engrafted cells of donor origin. Donor cell leukemia (DCL) was first recognized in 1971, but for many years, the paucity of reported cases suggested it to be a rare phenomenon. However, in recent years, an upsurge in reported cases (in parallel with advances in molecular chimerism monitoring) suggest that it may be significantly more common than previously appreciated; emerging evidence suggests that DCL might represent up to 5% of all posttransplant leukemia "relapses." Recognition of DCL is important for several reasons. Donor-derivation of the leukemic clone has implications when selecting appropriate therapy, because seeking to enhance an allogeneic GVL effect would intuitively not have the same role as in standard recipient-derived relapses. There are also broader implications for donor selection and workup, particularly given the growing popularity of nonmyeloblative HSCT and corresponding rising age of the potential donor pool. Identification of DCL raises potential concerns over future health of the donor, posing ethical dilemmas regarding responsibilities toward donor notification (particularly in the context of cord blood transplantation). The entity of DCL is also of research interest, because it might provide a unique human model for studying the mechanisms of leukemogenesis in vivo. This review presents and collates all reported cases of DCL, and discusses the various strategies, controversies, and pitfalls when investigating origin of posttransplant relapse. Putative etiologic factors and mechanisms are proposed, and attempts made to address the difficult ethical questions posed by discovery of donor-derived malignancy within a HSCT recipient.

Loss of the Y chromosome: an age-related or clonal phenomenon in acute myelogenous leukemia/myelodysplastic syndrome?

CONTEXT

The clinical association between loss of the Y chromosome and acute myelogenous leukemia and myelodysplastic syndrome (AML/MDS) has been debated because both phenomena are related to aging. A prior publication suggests that loss of the Y chromosome in more than 75% of cells may indicate a clonal phenomenon that could be a marker for hematologic disease.

OBJECTIVE

To evaluate the relationship between loss of the Y chromosome and AML/MDS.

DESIGN

A retrospective review of cytogenetic reports of 2896 male patients ascertained from 1996 to 2007 was performed. Results were stratified based on the percentage of cells missing the Y chromosome and were correlated with patients' ages and bone marrow biopsy reports through logistic regression analysis with adjustment for age.

RESULTS

Loss of the Y chromosome was found in 142 patients. Of these, 16 patients demonstrated myeloid disease, with 2 cases of AML and 14 cases of MDS. An increased incidence (P < .05) of AML/MDS was seen only in the group composed of 8 patients with complete loss of the Y chromosome in all karyotyped cells (1 case of AML and 7 cases of MDS).

CONCLUSION

Loss of the Y chromosome appears to be primarily an age-related phenomenon. However, in individuals in which all cells on cytogenetic analysis showed loss of the Y chromosome, there was a statistically significant increase in AML/MDS, suggesting that the absence of any normal-dividing cells in a bone marrow analysis may be indicative of AML/MDS.

Acquired biclonal chromosome X aberrations without autosomal chromosomal anomalies in acute myeloid leukemia

Acquired clonal chromosome X aberrations, whether numerical or structural, as the sole chromosomal anomaly in acute myeloid leukemia (AML) are very uncommon. The scarcity of nonconstitutional chromosome X aberrations detected in AML has prevented any meaningful evaluation of their prognostic significance. In this report, we describe the case of a patient with AML who had the unusual acquired karyotype of 45,X/-X,46,X,i(X)(q10) on presentation and 45,X,-X,add(19)(p13.3) on relapse. We also briefly review the literature on acquired numerical and structural chromosome X aberrations as the sole chromosomal anomaly in AML. This case adds to the sparse body of literature regarding chromosome X aberrations in AML. More case reports are needed to further elucidate the importance of such aberrations.

Frequencies and characterization of cytogenetically unrelated clones in various hematologic malignancies: seven years of experiences in a single institution

Cytogenetically unrelated clones are uncommon findings in hematologic disorders. In the present study, among the 1,110 various hematologic malignancies analyzed during the past seven years, 27 (2.4%) patients had karyotypically unrelated clones: 3.5% (7/202) of acute myeloid leukemias, 5.3% (11/206) of myelodysplastic syndromes, none of 40 acute lymphoblastic leukemias, 0.4% (1/233) of myeloproliferative disorders, and 2.6% (8/306) lymphoproliferative disorders with clonal chromosomal abnormalities. Twenty-five patients showed two unrelated clones and two had three unrelated clones. The most consistent chromosome abnormalities were del(5q) (seven cases), +8 (six cases), del(20q) (five cases), and del(7q), +12, +21, and -22 (three cases each). Of interest, the high frequency of different numeric or structural abnormalities affecting the same chromosomes in such clones supports the hypothesis that these karyotypically unrelated clones originate from the common malignant clone through submicroscopic molecular genetic changes and evolutionary processes.

Genomics of the human Y-chromosome. 1. Association with male infertility

The human Y chromosome contains over 60 million nucleotides, but least number of genes compared to any other chromosome and acts as a genetic determinant of the male characteristic features. The male specific region, MSY, comprising 95% of the Y chromosome represents a mosaic of heterochromatic and three classes of euchromatic (X-transposed, X-degenerate and ampliconic) sequences. Thus far, 156 transcription units, 78 protein-coding genes and 27 distinct proteins of the Y chromosome have been identified. The MSY euchromatic sequences show frequent gene conversion. Of the eight massive palindromes identified on the human Y chromosome, six harbor vital testis specific genes. The human male infertility has been attributed to mutations in the genes on Y chromosome and autosomes and failures of several physical and physiological attributes including paracrine controls. In addition, deletion of any one or all the three azoospermia (AZFa, AZFb or AZFc) factor(s) and some still unidentified regulatory elements located elsewhere in the genome result in infertility. Characterization of palindromic complexes on the long arm of Y chromosome encompassing AZFb and AZFc regions and identification of HERV15 class of endogenous retroviruses close to AZFa region have facilitated our understanding on the organization of azoospermia factors. Considerable overlap of the AZFb and AZFc regions encompassing a number of genes and transcripts has been shown to exist. However, barring details on AZF, information on the exact number of genes or the types of mutations prevalent in the infertile male is not available. Similarly, roles of sizable body of repetitive DNA present in close association with transcribing sequences on the Y chromosome are yet not clear. In a clinical setting with known cases of infertility, systematic search for loss or gain of these repeat elements would help understand their biological role(s). We present a brief overview on the genetic complexity of the human Y chromosome in the context of human male infertility.

Cytogenetics of chronic myeloproliferative disorders and related myelodysplastic syndromes

The only MPD associated with any specific chromosome anomaly is CML, which is linked with t(9;22)(q34;q11.2) or a variant of this anomaly. An association exists for del(13)(q12q14) and CIMF; t(5;12)(q33;p13) and CEL; and del(20q11), +8, and +9 and PV, but these anomalies can be seen in various hematologic malignancies. The most common chromosomal anomalies among MPD in order of frequency are t(9;22)(q34;q11.2), -Y, +8, +9, -7, del(20) (q11q13), del(13)(q12q14), del(5)(q13q33), and del(12)(p12). FISH techniques are useful for MPD to study inadequate bone marrow or blood specimens and to monitor disease status among patients with known chromosome anomalies, but they are not more sensitive than conventional chromosome studies.

Sex chromosome mosaicism in males carrying Y chromosome long arm deletions

Microdeletions of the long arm of the Y chromosome (Yq) are a common cause of male infertility. Since large structural rearrangements of the Y chromosome are commonly associated with a 45,XO/46,XY chromosomal mosaicism, we studied whether submicroscopic Yq deletions could also be associated with the development of 45,XO cell lines. We studied blood samples from 14 infertile men carrying a Yq microdeletion as revealed by polymerase chain reaction (PCR). Patients were divided into two groups: group 1 (n = 6), in which karyotype analysis demonstrated a 45,X/46,XY mosaicism, and group 2 (n = 8) with apparently a normal 46,XY karyotype. 45,XO cells were identified by fluorescence in-situ hybridization (FISH) using X and Y centromeric probes. Lymphocytes from 11 fertile men were studied as controls. In addition, sperm cells were studied in three oligozoospermic patients in group 2. Our results showed that large and submicroscopic Yq deletions were associated with significantly increased percentages of 45,XO cells in lymphocytes and of sperm cells nullisomic for gonosomes, especially for the Y chromosome. Moreover, two isodicentric Y chromosomes, classified as normal by cytogenetic methods, were detected. Therefore, Yq microdeletions may be associated with Y chromosomal instability leading to the formation of 45,XO cell lines.

Cytogenetic heterogeneity and clonal evolution in synchronous bilateral breast carcinomas and their lymph node metastases from a male patient without any detectable BRCA2 germline mutation

Two synchronous bilateral breast carcinomas and their matched lymph node metastases from a 70-year-old man were cytogenetically analyzed. All four tumors were near-diploid, and except for the primary tumor from the right breast, had a 45,X,-Y clone in common. The loss of the Y chromosome was, however, common to all four tumors, whereas metaphase cells from peripheral blood lymphocytes showed a normal 46, XY chromosome complement. The primary tumor from the right breast was monoclonal, with loss of the Y chromosome and gain of 1q, whereas its metastasis had two related clones: the 45,X,-Y clone, and the other a more complex version of the clone in the primary tumor, with inv(3), -14, and del(16)(q13) as additional changes. The primary tumor from the left breast was polyclonal with three unrelated clones: 45,X,-Y/45,XY,-18/47,XY,+20, two of which were present in its metastasis. DNA flow cytometric studies showed diploidy for both primary tumors. No mutation in the BRCA2 gene was found on analysis of DNA from peripheral blood lymphocytes. The present findings show that del(16)(q13) is a recurrent finding among male breast carcinomas and that some of the primary cytogenetic abnormalities, as well as the pattern of chromosomal changes during the progression of sporadic breast carcinoma in the male, are similar to those in the female. In addition, the loss of the Y chromosome in the tumors but not in peripheral blood lymphocytes, suggests a possible role for this abnormality in the pathogenesis of male breast carcinoma.

Myelodysplastic syndrome associated with monosomy 7 in a child with Bloom syndrome

Bloom syndrome is a genomic instability syndrome associated with predisposition to development of various types of malignancy. In this report, we described a 7-year-old boy with Bloom syndrome (BS) and myelodysplastic syndrome (MDS) associated with monosomy 7 and loss of the Y chromosome. To our knowledge, this was the first case with BS showing monosomy 7 and MDS during the early childhood period.

Loss of the Y chromosome in bone marrow cells: results on 1907 consecutive cases of leukaemia and preleukaemia

Loss of the Y chromosome with a resulting 45, X0 karyotype is observed in normal bone marrow cells of elderly males but also in haematological malignancies. Whether Y loss in neoplastic cells is related to the process seen in normal ageing or is part of the carcinogenic process is unknown. The present study concerns the cytogenetic data from 1907 consecutive leukaemic or preleukaemic male patients with special regard to the presence or absence of the Y chromosome. Sixty-five patients (3.4%) had a 45, X-Y clone in their bone marrow (BM) cells. Loss of Y was rare below the age of 50 but increased in older patients, reaching 25% of the men over 80. Sixteen patients (0.08%) had more than 90% X0 cells in their BM. A correlation between Y loss and leukaemia could be established in seven cases, three of which were acute myeloid leukaemia M2 subtype where -Y is known to be a secondary event. In three other cases, -Y was part of a complex karyotype. Only one patient exhibited a 45, X0 karyotype, with no other rearrangement, that could be positively correlated with the neoplastic process.

Monosomy X as the sole cytogenetic abnormality in acute lymphoblastic leukemia: a report of two new patients

Monosomy X as the sole acquired cytogenetic abnormality is usually found in myeloid hematological malignancies, especially those with myelodysplastic features. Only three cases of acute lymphoblastic leukemia (ALL) with this abnormality have been previously reported. We add two cases to this series and comment on the likelihood of a tumor suppressor gene being located on the X chromosome.

Monosomy X as a recurring sole cytogenetic abnormality associated with myelodysplastic diseases

Solitary loss of the X chromosome is associated with Turner syndrome and not hematological disorders. We describe five patients with non-constitutional loss of the X chromosome as the sole cytogenetic abnormality in their bone marrow. Three of the five patients had myelodysplastic syndrome (MDS), one case had AML M-6 with evidence suggestive of an evolving MDS, and the last patient had a dysplastic marrow. A review of the literature identified sporadic reports of an association of monosomy X and several hematologic disorders, as well as a few solid tumors. In this series of patients, monosomy X as a sole non-constitutional cytogenetic abnormality in bone marrow is associated with myelodysplastic diseases. In addition, fluorescence in situ hybridization analysis with an X centromere probe indicated that monosomy X was present in erythroid precursors, myeloblasts, promyelocytes, myelocytes, metamyelocytes, granulocytes, and monocytes, while mature lymphocytes presented with two copies of the X chromosome. The molecular cytogenetic evidence supports the diagnosis of a myelodysplastic disorder in these cases and documents the potential role of FISH in hematological disease.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.

Trisomy 15 in hematological malignancies: six cases and review of the literature

We report six cases of trisomy 15 in patients with hematological malignancy. In four cases trisomy 15 was the sole abnormality and in two cases it was associated with sex chromosome loss. The patient age range was 6-91 years, and three patients were male. Four patients had myelodysplasia (refractory anemia), one patient each had acute myeloid leukemia and acute lymphoblastic leukemia. A literature review identified ten other cases of trisomy 15 as the sole abnormality in hematological malignancies. Trisomy 15 as the sole autosomal abnormality in hematological malignancy is uncommon, but can occur in both myeloid and lymphoid malignancies. It appears to occur most frequently in myelodysplasia.

Y chromosome aneuploidy, micronuclei, kinetochores and aging in men

This investigation was conducted to determine the relationship between Y chromosome loss and increased micronucleus formation with age. We also investigated the status of kinetochore proteins in the micronuclei. Umbilical cord blood samples were obtained from 18 newborn males, and peripheral blood was obtained from 35 adult males ranging in age from 22 to 79 years. Isolated lymphocytes from all 53 donors were cultured and blocked with cytochalasin B. Two thousand binucleate cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. This assay showed 23.8% of the micronuclei to be kinetochore-positive, while 76.2% of the micronuclei were kinetochore-negative. Cells were then hybridized with a 3.56-kb biotinylated Y chromosome-specific probe. All micronucleate cells were relocated and their Y probe status was determined. A significant increase in Y-bearing micronuclei with age was observed. Metaphase cells from the same samples were analyzed for the presence or absence of Y chromosome. The relationship between Y chromosome-positive micronuclei and Y chromosome-negative metaphase cells was highly significant, suggesting that Y chromosome-deficient metaphase cells result from cells which had previously lost a Y chromosome due to micronucleation. The cause of micronucleus formation from a lagging Y chromosome appears probably to be either a faulty or a diminished amount of kinetochore protein.

Chromosome X numerical abnormalities in patients with non-Hodgkin's lymphoma. A study of 59 patients using fluorescence in situ hybridization

Chromosome X numerical abnormalities are frequently observed in non-Hodgkin's lymphoma (NHL), with an incidence of 3% to 14% for chromosomal loss and 7% to 33% for chromosomal gain. Because sex chromosome numerical abnormalities are thought to be due to aging, little information is known about their relation to gender, therapy, and prognosis. Therefore, to determine the incidence and clinical relevance of this abnormality in NHL, we studied specimens from 59 NHL patients (31 men and 28 women) by fluorescence in situ hybridization (FISH) using a directly conjugated centromeric probe for chromosome X. The median age for the entire group was 52 years (range, 31-88 years). All specimens were obtained by fine-needle aspiration of diseased lymph nodes. Sex-matched lymphocytes from benign hyperplastic lymph nodes were used as controls. The overall incidence of chromosome X numerical abnormalities was 49.2%. Female patients had a higher overall incidence than males (76% vs. 24%; p < 0.001). The median percentage of cells involved in this abnormality in each specimen was 5.2%. There was no statistically significant difference in the incidence in previously treated than untreated patients (53.1% vs. 44.4%; p < 0.75) and in intermediate-grade NHL than low-grade NHL (61.1% vs. 50%; p < 0.75). There was a trend towards a higher incidence of chromosome X loss in older patients. While the difference in the incidence of chromosome X abnormalities observed between women and men may be due to the difference in the normal copy numbers of this chromosome in each sex group, this abnormality remained higher than any other autosomal chromosome abnormality in NHL previously evaluated by FISH. We conclude that, although FISH detected a high incidence of chromosome X numerical abnormalities and that females had a higher incidence than males, only a small percentage of the cells were involved, suggesting that this abnormality is most likely a secondary genetic defect that is not important in the pathogenesis of NHL.

Prediction of 18-month survival in patients with primary myelodysplastic syndrome. A regression model and scoring system based on the combination of chromosome findings and the Bournemouth score

The predictive potential of six selected factors was assessed in 72 patients with primary myelodysplastic syndrome using univariate and multivariate logistic regression analysis of survival at 18 months. Factors were age (above median of 69 years), dysplastic features in the three myeloid bone marrow cell lineages, presence of chromosome defects, all metaphases abnormal, double or complex chromosome defects (C23), and a Bournemouth score of 2, 3, or 4 (B234). In the multivariate approach, B234 and C23 proved to be significantly associated with a reduction in the survival probability. The similarity of the regression coefficients associated with these two factors means that they have about the same weight. Consequently, the model was simplified by counting the number of factors (0, 1, or 2) present in each patient, thus generating a scoring system called the Lausanne-Bournemouth score (LB score). The LB score combines the well-recognized and easy-to-use Bournemouth score (B score) with the chromosome defect complexity, C23 constituting an additional indicator of patient outcome. The predicted risk of death within 18 months calculated from the model is as follows: 7.1% (confidence interval: 1.7-24.8) for patients with an LB score of 0, 60.1% (44.7-73.8) for an LB score of 1, and 96.8% (84.5-99.4) for an LB score of 2. The scoring system presented here has several interesting features. The LB score may improve the predictive value of the B score, as it is able to recognize two prognostic groups in the intermediate risk category of patients with B scores of 2 or 3. It has also the ability to identify two distinct prognostic subclasses among RAEB and possibly CMML patients. In addition to its above-described usefulness in the prognostic evaluation, the LB score may bring new insights into the understanding of evolution patterns in MDS. We used the combination of the B score and chromosome complexity to define four classes which may be considered four possible states of myelodysplasia and which describe two distinct evolutional pathways.